Byungje Lee

A Dual-Band Wilkinson Power Divider

A new scheme is proposed for the dual-band operation of the Wilkinson power divider/combiner. The dual band operation is achieved by attaching two central transmission line stubs to the conventional Wilkinson divider. It has simple structure and is suitable for distributed circuit implementation.

Dual-band, cross coupled branch line coupler

A novel branch line coupler structure is proposed with application to the dual band operation. The proposed structure has additional cross coupling branches to the conventional branch hybrid coupler. Additional design freedom can be obtained using the proposed scheme, which can serve many useful purposes such as the dual band operation of the branch line coupler.

Miniature microstrip antenna with a partially filled high-permittivity substrate

A new technique to reduce the overall dimension of a microstrip antenna using a partially filled high-permittivity substrate is proposed. The miniaturized microstrip antenna for a repeater system in a mobile communication cellular band (824-894 MHz) is designed with the proposed technique and manufactured with light weight and small size. Comparison between simulations, based on HP HFSS software, and measurements are provided.

Dual-Band Branch-Line Coupler With Port Extensions

A new branch-line coupler structure with port extensions is proposed for the dual-band operation. The conventional branch-line coupler structure is adapted to the dual-band operation by inserting a transmission line section at the input ports and modifying the branch parameters. The dual-band performance of the proposed coupler is verified theoretically through the rigorous microwave circuit analysis and the exact design equations are derived in concise form. The design, simulation, and measurement results validate the dual-band capability of the proposed coupler with the same quadrature phase relation between the two band frequencies.

Compact UWB Antenna With I-Shaped Band-Notch Parasitic Element for Laptop Applications

A compact ultrawideband (UWB) antenna with a band-notch function is proposed for laptop applications. The band-notch function is realized by a half-wavelength parasitic element printed on the rear side of the substrate. The impedance bandwidth (VSWR < 2) of the antenna is 3.1 ~ 11.4 GHz (114%) with a notched frequency from 5.05 to 5.90 GHz. The antenna has a fairly good omnidirectional pattern, and the average gain is -3.0 ~ -1.2 dBi over the UWB frequency band except for the notched frequency band. The performance of the proposed antenna is confirmed by simulation and measurement results.

Stubbed Branch Line Balun

A new impedance transforming balun scheme is presented based on the branch line structure with stubs on the vertical branches. The stubbed vertical branch eliminates the unwanted even mode output and provides only the required balun output with opposite phase. Also, the use of stubs reduces the branch lengths by two times the stub length and therefore, helps to reduce the total size of the proposed balun

Ku-band high efficiency antenna with corporate-series-fed microstrip array

Excellent efficiency of a linearly polarized microstrip array in Ku-band is achieved by having proper impedance matching throughout the array and by properly using the corporate and series fed by microstrip transmission lines. The cavity-backed microstrip patch is used to obtain relatively wide bandwidth. The auto-tracking Ku-band antenna in the azimuth direction has developed with a very low profile for vehicles rooftop mounting, as well as, a low manufacturing cost. The main beam of array is tilted 15/spl deg/ away from the broadside direction to provide optimum coverage for Korea satellite III.

A Compact Frequency-Reconfigurable Multiband LTE MIMO Antenna for Laptop Applications

A compact frequency-reconfigurable multipleinput-multiple-output (MIMO) antenna on a laptop is proposed for multiband LTE services. Each MIMO antenna consists of two planar inverted-F antenna (PIFA) elements, using a T-shaped dc line and two p-i-n diodes (D1 and D2), in conjunction with the proximity-coupled feed structure. By effectively minimizing its dimension and its interference with antenna performance, the proposed T-shaped dc line is designed to fit within the proximity-coupled feed structure. The proposed MIMO antenna covers the LTE 17/13 bands (704-787 MHz, VSWR <; 3) at State 1 (D1 and D2: ON state), and the LTE 20/7 bands (791-862 MHz, 2500-2690 MHz, VSWR <; 3) at State 2 (D1 and D2: OFF state). The proposed antenna obtains high isolation (> 20 dB), low envelope correlation coefficient (ECC <; 0.0161), and total efficiency of greater than 51%, for all operating frequency bands.

Closely Mounted Mobile Handset MIMO Antenna for LTE 13 Band Application

A compact (60 × 15 × 5 mm 3) mobile handset multiple-input-multiple-output (MIMO) antenna for LTE 13 band (746-787 MHz) applications is proposed. The antenna consists of two symmetrical planar inverted-F antennas (PIFAs) in conjunction with a T-shaped common radiator. Without using any additional coupling elements between these closely mounted antennas, both high isolation ( > 17 dB) and low envelope correlation coefficient (ECC <; 0.05 ) are achieved. The low ECC is achieved by using diagonally orthogonal radiation patterns from optimized locations of the MIMO antenna feeds and elements. Low mutual coupling achieved by using the T-shaped common radiator gives rise to the high isolation.

Balanced RFID Tag Antenna Mountable on Metallic Plates

A novel balanced tag antenna for a radio frequency identification (RFID) system is presented. The radiating elements of two planar inverted-F antennas (PIFAs) are inductively coupled by the feed loop with out of phase. The balanced structure provides smaller degradation of performances when an RFID tag is mounted on various sizes of metal plates. The HFSS simulator is employed to analyze the proposed antenna in the design process and to compare with measured results